chamilo-lms blank page and error after installation

Question

I am new to chamilo installation, I am having this issue after the installation with chamilo-lms. After I login, and try to go to home page, it becomes a blank page. Also, when clicking on Calendar/Administration for example I receive these errors:

I would be very grateful If someone could help me with same directions. Thanks a lot!

CRITICAL 10:25:05

    {
    "exception": {}
   }
CRITICAL
10:25:05
request Uncaught PHP Exception Exception: "You are not allowed" at /var/www/chamilo/public/main/inc/lib/api.lib.php line 3451
{
    "exception": {}
}`
`
ExceptionLogs 2Stack Trace
Exception
Exception:
You are not allowed

  at public/main/inc/lib/api.lib.php:3451
  at api_not_allowed()
     (public/main/inc/lib/api.lib.php:1126)
  at api_block_anonymous_users()
     (public/main/auth/my_progress.php:10)    `